FYI, we noticed the following commit (built with gcc-7):

commit: 9fe41efaca08416657efa8731c0d47ccb6a3f3eb ("tracing: Add synth event generation test module")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: rcuperf
with following parameters:

	runtime: 300s
	perf_type: rcu



on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+---------------------------------------------+------------+------------+
|                                             | 8dcc53ad95 | 9fe41efaca |
+---------------------------------------------+------------+------------+
| boot_successes                              | 4          | 0          |
| boot_failures                               | 0          | 4          |
| BUG:unable_to_handle_page_fault_for_address | 0          | 4          |
| Oops:#[##]                                  | 0          | 4          |
| EIP:strscpy                                 | 0          | 4          |
| Kernel_panic-not_syncing:Fatal_exception    | 0          | 4          |
+---------------------------------------------+------------+------------+


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <rong.a.chen@intel.com>


[    3.208397] BUG: unable to handle page fault for address: ffffffff
[    3.209051] #PF: supervisor read access in kernel mode
[    3.209588] #PF: error_code(0x0000) - not-present page
[    3.210192] *pdpt = 0000000002a22001 *pde = 0000000002a24063 *pte = 0000000000000000 
[    3.210583] Oops: 0000 [#1] PREEMPT PTI
[    3.210583] CPU: 0 PID: 1 Comm: swapper Not tainted 5.5.0-rc6-00065-g9fe41efaca084 #1
[    3.210583] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    3.210583] EIP: strscpy+0x140/0x190
[    3.210583] Code: 21 f9 81 e1 80 80 80 80 74 a0 e9 6b ff ff ff 8d 76 00 8b 45 ec 85 c9 74 41 8d 1c 02 8d 3c 06 eb 09 8b 4d f0 89 f7 89 d3 31 c0 <0f> b6 1b 88 1f 84 db 74 31 8d 58 01 8d 3c 08 eb 15 8d b4 26 00 00
[    3.210583] EAX: 00000000 EBX: ffffffff ECX: 00000020 EDX: ffffffff
[    3.210583] ESI: ec65d26c EDI: ec65d26c EBP: ec769e34 ESP: ec769e20
[    3.210583] DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 EFLAGS: 00010246
[    3.210583] CR0: 80050033 CR2: ffffffff CR3: 02a26000 CR4: 000406b0
[    3.210583] Call Trace:
[    3.210583]  synth_event_trace+0x241/0x2b0
[    3.210583]  synth_event_gen_test_init+0xeb3/0xf04
[    3.210583]  ? print_synth_event+0x450/0x450
[    3.210583]  ? init_trace_printk+0x2b/0x2b
[    3.210583]  do_one_initcall+0xc5/0x220
[    3.210583]  ? do_one_initcall+0xc5/0x220
[    3.210583]  kernel_init_freeable+0x137/0x19b
[    3.210583]  ? rest_init+0xf0/0xf0
[    3.210583]  kernel_init+0xd/0x110
[    3.210583]  ret_from_fork+0x2e/0x38
[    3.210583] Modules linked in:
[    3.210583] CR2: 00000000ffffffff
[    3.210583] ---[ end trace d4429bd882710c19 ]---


To reproduce:

        # build kernel
	cd linux
	cp config-5.5.0-rc6-00065-g9fe41efaca084 .config
	make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 olddefconfig prepare modules_prepare bzImage

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email



Thanks,
Rong Chen